Roof coatings constitute an upper finish on roofs. Roof coatings protect the roofs and hence also the entire constructions from effects of weathering, more particularly from rain, dew, mist, snow or extreme temperatures. Roof coatings, therefore, are not walls and also not the roof structure, i.e., not the framework of roofs, but instead are an outer skin which is applied to the framework of roofs. Roof coatings are therefore applied on the outer surface of roofs, i.e., on the side of roofs that faces the environment, and not on the inside, i.e., the side facing the interior of buildings. Roof coatings, then, are an outer layer, and preferably the outermost layer, of a roof.
For roof coatings, as alternatives to roofing shingles or concrete, a range of alternatives have been proposed, such as, for example, roof coatings on a bituminous basis, such as roofing felt, or on a polymeric basis, such as EPDM (polymers based on ethylene, propylene, and diene monomers), epoxy (self-crosslinking polymers containing epoxy groups) or PU (polyurethane systems). These systems may be applied in the form of sheets, panels or in liquid form. Also commonplace are TPO films (thermoplastic polyolefin films) or poly-acrylates in liquid form. Existing liquid systems, especially aqueous systems, usually require long drying times upon their application, until the desired roof coatings are obtained. This disadvantage comes to bear particularly under cool or damp conditions. Moreover, during the drying process, there is always the risk of mechanical damage to the coating. In the case of sheets or panels, there is a risk of mechanical damage in the course of transportation to the construction site, or during application on the construction site. Furthermore, the coating of a roof necessitates a large number of panels or sheeting webs, which must be bonded adhesively in order to produce an assembly. These bonding sites, however, are a source of damage as a consequence of deficient bonding or aging, and this may lead to leaks and, ultimately, to failure of the roof coating. Lastly, at application thicknesses in the region of 3 mm, the common aqueous systems exhibit little sag resistance, and this necessitates the use of reinforcing fabric or cladding.